Impact of body surface area on efficacy and safety in patients with EGFR-mutant non-small cell lung cancer treated with osimertinib as a first-line treatment.

Background: The most recommended treatment for stage IV EGFR-positive lung cancer is osimertinib monotherapy. The dosage of osimertinib is fixed at 80 mg/day regardless of body surface area (BSA), however some patients withdraw or reduce the dosage due to adverse events (AEs).
Methods: We performed a retrospective cohort study of 98 patients with EGFR mutation-positive non-small cell lung cancer (NSCLC), who received 80 mg osimertinib as the initial treatment. We investigated the impact of BSA on efficacy and safety of osimertinib.
Results: The cut-off value of BSA was estimated using the receiver operating characteristics curve, and was determined to be 1.5 m ² . There were 44 patients in the BSA < 1.5 group and 54 patients in the BSA ≥ 1.5 group. There was no significant difference in the incidence of AEs (hematologic toxicity of ≥grade 3 or higher, and non-hematologic toxicity of ≥grade 3) between the two groups. However, the incidence of dose reduction due to AEs was significantly higher in the BSA < 1.5 group compared with the BSA ≥ 1.5 group (16 patients vs 5 patients, p = 0.003). The main reasons were fatigue, anorexia, diarrhea, and liver disfunction. Median progression-free survival (PFS) was not significantly different (16.9 months in the BSA < 1.5 group vs 18.1 months in the BSA ≥ 1.5 group, p = 0.869).
Conclusion: Differences in BSA affected the optimal dose of osimertinib. However, the PFS with osimertinib treatment was not affected by BSA. Therefore, when using osimertinib as an initial treatment for patients with EGFR-mutant NSCLC, dose reduction to control AEs should be considered, especially in the BSA<1.5 group.
Competing Interests: Declaration of competing interest Motohiro Tamiya has received lecture fees from Chugai Pharmaceutical, Boehringer Ingelheim, AstraZeneca, Taiho Pharmaceutical, Eli Lilly, Novartis, Pfizer, Asahi Kasei Pharmaceutical, Ono Pharmaceutical, Bristol-Myers Squibb, MSD, Bayer, Amgen, Kyowa-Kirin, and Nippon Kayaku. Kei Kunimasa has received lecture fees from AstraZeneca, Chugai Pharma and Novartis. Kazumi Nishino has received lecture fees from AstraZeneca, Chugai Pharmaceutical, Boehringer Ingelheim, Eli Lilly, Roche Diagnostics, Novartis, Pfizer, Merk, Janssen Pharmaceutical K.K., Bristol Myers Squibb, and Nippon Kayaku. Mari Takagi has received lecture fees from Eli Lilly, Yakult, Terumo, Chugai Pharmaceutical, Towa Pharmaceutical, Daiichi-Sankyo, Becton Dickinson and Company, MSD, Taiho Pharmaceutical, Nippon Kayaku, AstraZeneca, Sando, and Ono Pharmaceutical. Other authors have no conflicts of interest to declare.
(Copyright © 2024. Published by Elsevier Ltd.)